How water is used in the Murray-Darling Basin

• Water is allocated to irrigators in the Murray-Darling

Basin by state governments, who have their own licences and set of rules • Irrigators decide how to use their allocation, i.e. irrigate, store, trade or leave unused. • Bulk sharing arrangement in the southern basin are set by the authority • Water accounting over the long term is based on sustainable diversion limits

Debate and dispute have surrounded management and use of water in the MurrayDarling Basin for some time, with droughts, changing crop types and climate change serving to increase this pressure on policy makers and water users. The Murray-Darling Basin Authority has provided a simple explanation of how water is used by and allocated to the many different agricultural industries in the in the basin.

Water is allocated to irrigators based on water availability and rules set out by different Basin governments. Each state has developed its own set of licences and rules around how to allocate water to their entitlement holders. This means allocations, water orders and delivery of water all work in a different way from state to state.

Some entitlements are more reliable than others, meaning some entitlement holders receive an allocation most years, while other allocations are more variable depending on rules and rainfall.

Water can be used, stored, traded or reallocated

When water is allocated to irrigators by their state authority, it is up to individuals to determine how they use their water, based on their own business needs. Irrigators can choose to: • use their allocation on their farm • trade all or some of their allocation to another water user • buy an allocation off another water user and use that water for their farm • save water for the next irrigation year – this is called carryover (some licence types limit whether water can be carried over) • leave their water un-used, which means it stays in the dam and returns to the state’s pool for re-allocation.

Not all water allocated to an irrigator is used. Some water is saved by individuals for the next water season—this means they have water in reserve.

Carrying water over is based on individual business needs and license types. Not all licences allow for water to be carried over.

This water is considered ‘unused’, but that does not mean it is available for re-allocation. It is still owned by the irrigator.

Bulk water sharing arrangements in the southern Basin are set by the Murray-Darling Basin Agreement, which provides the rules for sharing arrangements between NSW, Victoria and South Australia.

Each state has developed its own set of licences and rules around how to allocate the state’s share of water to their entitlement holders. This means allocations, water orders and delivery of water all work in a different way from state to state and will continue to do so.

The sustainable diversion limits (SDL) water accounting system monitors water trends over the long-term, importantly this is not the system used for allocations, water sharing between the states, or daily river operations.

The SDL water accounting system ensures states remain on-track over the long term regarding their water use and assists water managers to consider future trends and demands. The SDL accounting system does not focus on individual water users and water deliveries.

Bulk water supply

The MDBA calculates the amount of water available in the River Murray and provides NSW, VIC and SA with an agreed share (based on the MDB Agreement)

No previous allocation carried over

State governments allocate water to entitlement holders as per their allocation frameworks. Some entitlements are more reliable than others, meaning some entitlement holders receive an allocation most years, while other allocations are more variable

States provide water use data to the MDBA annually for assessment. The MDBA assesses water use over multiple years to determine trends in use and compliance with limits

State

Allocation 20 ML

It is up to individual irrigators to decide what they do with their allocation

Allocation 15 ML Trade $

Use 20 ML

Use 5 ML

Carryover – Some irrigators choose to store water for use the following year, based on their business needs and their license type

Carryover 10 ML

Allocation carried over from previous year Carryover 10 ML

*This is an example of how water use can occur in the River Murray system and is not a representation of actual use. Allocation 7 ML

Allocation 6 ML

Use 11 ML

Irrigators can use previous carryover as part of their annual allocation

Use 4 ML Carryover 6 ML

Unused 2 ML

Some irrigators may no longer need their full allocation but are limited with what they can do with their water so it returns to the consumptive pool for reallocation

FIGURE. AN EXAMPLE OF HOW WATER USE CAN OCCUR IN THE RIVER MURRAY SYSTEM (DOES NOT REPRESENT ACTUAL USE).

Source: MDBA website

Source: This article is from MDBA website.